IN a shocking expose of gun violence in America, The Huffington Post has compiled a list of every US shooting death since the Sandy Hook Elementary School massacre on December 14.

That act of violence claimed the lives of 26 people, including 20 innocent children, at a school in Connecticut.

The Huffington Post reports that the night after Sandy Hook, a gunman pulled behind a car in Kansas City and opened fire, striking a 4-year-old boy in the head.

"He was innocent and he was just lifeless," a bystander said. "All my life I’ve never seen nothing so devastating."

This week doctors declared the boy brain dead.

In the week following the Sandy Hook massacre, bodies were found inside a vacant house, at a car wash, and in a corner store. They were also discovered on a bike trail, in a backyard, inside the front office of a motel, and in a Chevy pickup, the website reports. All of the bodies had one thing in common: they died from gunshots wounds.

The Huffington Post spent this week tracking gun-related homicides and accidents throughout the US, and logged more than 100 from Google and Nexis searches. It says there were more than twice that many homicides alone in an average week in 2010.

The deaths included murder-suicides, and ranged from babies through to grandparents.

On Saturday afternoon, a 3-year-old in Oklahoma died after accidentally shooting himself in the head with a gun he found inside his aunt and uncle's house. His uncle is an Oklahoma state trooper.

"Nobody should have to go through something like that," a resident said.

Paul Sampleton Jr., 14, was bound and shot in his Georgia townhome on Wednesday afternoon. His father found him in the kitchen. Police suspect a robbery motive, the website reports.

"He was smiling, listening to music," a friend told a local reporter. "He got on his bus, I got on mine. We were all happy."

The list goes on.

The expose comes as US President Barack Obama has vowed to take action to stop gun violence and gun lobby group NRA was slammed for calling for armed police in every US school.

Mr Obama's promise came in response to online petitions signed by more than 400,000 people after last week's primary school massacre, as the US's most powerful pro-gun lobbying group demanded overnight that armed police be deployed to every school in the country.

"In the days since the heartbreaking tragedy in Newtown, Connecticut, hundreds of thousands of you, from all 50 states, signed petitions asking us to take serious steps to address the epidemic of gun violence in this country," Mr Obama said in an online video on Friday. "We hear you."

Mr Obama joined a nationwide moment of silence to mark the passing of one week since the Newtown school massacre overnight. Mr Obama took part in the unofficial national day of mourning at the White House and First Lady Michelle Obama sent an open letter of support for the survivors.

The National Rifle Association (NRA), which defends what it sees as US citizens' constitutional right to bear arms, had been under pressure to respond in the wake of last week's massacre of 20 young children and six school staff.

But the group's leaders, in a combative and determined public appearance, ceded no ground to those calling for tougher gun laws.

"The only thing that stops a bad guy with a gun is a good guy with a gun," declared NRA vice-president Wayne LaPierre, in the group's first reaction since last week's massacre of 26 children and staff in an elementary school.

"I call on Congress today to act immediately to appropriate whatever is necessary to put armed police officers in every single school in this nation," he said, in a lengthy statement. He took no questions from reporters.

The NRA was ready to help train security teams for schools and work with teachers and parents to improve security measures, and attacked the media and the political class for what he said was demonising gun owners, he said.

The declaration caused outrage with his armed-officers idea immediately lambasted by gun control advocates, and not even the NRA's point man on the effort seemed willing to go so far.

Former Republican congressman Asa Hutchinson of Arkansas, whom LaPierre named national director of the program, said in an interview that decisions about armed guards in schools should be made by local districts.

"I think everyone recognises that an armed presence in schools is sometimes appropriate,'' Hutchinson said. "That is one option. I would never want to have a mandatory requirement for every school district to have that.''

Democratic congressman Jerrold Nadler of New York called the NRA's response "both ludicrous and insulting'' and pointed out that armed personnel at Columbine High School in Colorado and the Fort Hood Army post in Texas could not stop mass shootings.

The liberal group CREDO, which organised an anti-NRA protest outside congress, called LaPierre's speech "bizarre and quite frankly paranoid''.

"This must be a wake-up call even to the NRA's own members that the NRA's Washington lobbyists need to stand down and let congress pass sensible gun control laws now,'' CREDO political director Becky Bond said in a statement.

New York City Mayor Michael Bloomberg said the NRA is blaming everyone but itself for a national gun crisis and is offering "a paranoid, dystopian vision of a more dangerous and violent America where everyone is armed and no place is safe''.

The statement did not impress Chris Murphy, the congressman who represents the district that includes the school.

"Walking out of another funeral and was handed the NRA transcript. The most revolting, tone deaf statement I've ever seen,'' he said, on Twitter.

And the statement immediately drew criticism from supporters of tougher gun control, who are pushing to ban semi-automatic assault weapons like the .223 Bushmaster rifle that the gunman used in the December 14 shooting.

"The NRA leadership's drive to fill our schools with more deadly guns and ammo is wildly out of touch with responsible gun owners and the American public,'' New Jersey Senator Frank Lautenberg said.

The New York Times, in an editorial on Saturday, did not mince words, calling LaPierre's remarks a "mendacious, delusional, almost deranged rant''.

Mr Obama has called on Congress to pass legislation banning military-style assault rifles and high-capacity ammunition clips. It would would also close loopholes that allow people to purchase guns without background checks.

Mr Obama has also appointed US Vice President Joe Biden to head a task force to explore ways to prevent mass shootings, including by improving access to mental health care, and addressing depictions of violence in popular culture.

"I will do everything in my power as president to advance these efforts, because if there's even one thing we can do as a country to protect our children, we have a responsibility to try," Mr Obama said in the video. "But as I said earlier this week I can't do it alone. I need your help."

Mr Obama called on ordinary citizens, law enforcement officials and gun owners to campaign publicly and petition Congress in support of his reforms.

More than 400,000 people have signed "We the People" petitions on the White House's website calling for action on gun violence, making it one of the most popular issues since the launch of the site, a White House official said.

One such petition set the record for being the fastest ever to reach 25,000 signatures, the official said.

Last Friday's massacre of 26 people, including 20 children, at Sandy Hook Elementary School - the latest in a series of mass shootings over the past two years - has galvanised support for reforms aimed at stemming gun violence.

America has suffered an epidemic of gun violence over the last three decades including 62 mass shooting incidents since 1982. The vast majority of weapons used have been semi-automatic weapons obtained legally by the killers.

There were an estimated 310 million non-military firearms in the United States in 2009, roughly one per citizen, and people in America are 20 times more likely to be killed by a gun than someone in another developed country.

But the NRA's Mr LaPierre insisted gun ownership was not the problem.

"You know, five years ago after the Virginia Tech tragedy when I said we should put armed security in every school, the media called me crazy," he said, referring to a 2007 campus shooting that left 32 people dead.

"But what if, what if when Adam Lanza started shooting his way into Sandy Hook Elementary School last Friday he'd been confronted by qualified armed security?" he demanded.

"Will you at least admit it's possible that 26 little kids - that 26 innocent lives might have been spared that day? Is it so abhorrent to you that you'd rather continue to risk the alternative?"

The statement immediately drew criticism from supporters of tougher gun control, who are pushing to ban semi-automatic assault weapons like the .223 Bushmaster rifle that Lanza used in the shooting.

"The NRA leadership's drive to fill our schools with more deadly guns and ammo is wildly out of touch with responsible gun owners and the American public," New Jersey's Senator Frank Lautenberg said on Twitter.

The protesters that attempted to drown out LaPierre's statement were more blunt. One bore a banner reading "NRA kills our kids" the other "NRA has blood on its hands." They were led away by security.

Earlier, the US came together for a moment of silence in memory of the victims. Connecticut State Governor Dannel Malloy first called on residents to stop and reflect in silence at 9.30am (1.30am AEDT) local time, the minute 20-year-old Adam Lanza burst into the Sandy Hook Elementary School and began slaughtering 20 six- and seven-year-old children and six staff on December 14.

"Let us all come together collectively to mourn the loss of far too many promising lives," Mr Malloy said.

"Though we will never know the full measure of sorrow experienced by these families, we can let them know that we stand with them during this difficult time."

Mr Malloy asked for churches and government buildings to ring bells 26 times, symbolizing each of the victims in the school.

In Newton, bell rang as people on the street stood in a cold, driving rain.

His appeal was quickly matched by state governors from Hawaii to Florida, who called on residents to observe their own moment of silence at 9.30am local time in solidarity. Houses of worship around the country also embraced the week's anniversary.

The National Council of Churches said that thousands of churches would "observe a minute of silence and at 9.30am Friday sound their bells 26 times in memory of the victims who died in the school."

On the crowd-sourced charity site, causes.com, almost 177,000 people had signed up by early Friday to pledge a moment's silence.

Mrs Obama wrote to the people of Newtown that "as a mother of two young daughters, my heart aches for you and your families."

However, "the countless acts of courage, kindness and love here in Newtown and across America" had inspired her to believe the country had shown its good side in the aftermath of the massacre, she said.

News.com.au's Privacy Policy includes important information about our collection, use and disclosure of your personal information (including to provide you with targeted content and advertising based on your online activities). It explains that if you do not provide us with information we have requested from you, we may not be able to provide you with the goods and services you require. It also explains how you can access or seek correction of your personal information, how you can complain about a breach of the Australian Privacy Principles and how we will deal with a complaint of that nature.

A NOTE ABOUT RELEVANT ADVERTISING: We collect information about the content (including ads) you use across this site and use it to make both advertising and content more relevant to you on our network and other sites.